Eur J Pediatr (1993) 152:128-131 EuropeanJournal of Pediatrics 9 Springer-Verlag1993 Meal-induced thermogenesis in obese children with or without familial history of obesity C. Maffeis 1, Y. Schutz 2, L. Zoccante l, and L. Pinelli 3 1 Regional Centre for Juvenile Diabetes, Institute of Paediatrics, University of Verona Policlinico, 1-37134 Verona, Italy 2Institute of Physiology, University of Lausanne, Rue de Bugnon 7, CH-1011 Lausanne, Switzerland 3 Chair of Preventive and Social Paediatrics, University of Verona, Italy Received September 27, 1991 / Accepted after revision May 18, 1992 Abstract. Resting metabolic rate (RMR) and the thermic effect of a meal (TEM) were measured in a group of 26 prepubertal children divided into three groups: (1) chil- dren with both parents obese (n = 8, group OB2); (2) chil- dren with no obese parents and without familial history of obesity (n = 8, OB0); and (3) normal body weight chil- dren (n = 10, C). Average RMR was similar in OB2 and OB0 children (4785 + 274 kJ/day vs 5091 _+ 543 kJ/day), but higher (P < 0.05) than in controls (4519 + 322 kJ/day). Adjusted for fat-free mass (FFM) mean RMRs were com- parable in the three groups of children (4891 + 451 kJ/day vs 5031 + 451 kJ/day vs 4686 + 451 kJ/day in OB2, OB0, and C, respectively). The thermic response to the mixed meal was similar in OB2, OB0 and C groups. The TEM calculated as the percentage of RMR was lower (P < 0.05) in obese than in control children: 10.2% + 3.1% vs 10.9% + 4.3% vs 14.0% + 4.3% in OB2, OB0, and C, respec- tively. The similar RMR as absolute value as well as ad- justed for FFM, and the comparable thermic effect of food in the obese children with or without familial his- tory of obesity, failed to support the view that family his- tory of obesity can greatly influence the RMR and the TEM of the obese child with obese parents. Key words: Resting metabolic rate - Meal induced thermo- genesis - Obesity - Children - Familial dependence Introduction The mechanisms by which the pathogenetic factors of obesity might influence energy balance include alter- ation in caloric intake, expenditure, or both. It has been suggested that a reduction of the energy expenditure, either due to a low resting metabolic rate (RMR), blunted postprandial thermogenesis, and/or re- duced energy expenditure for physical activity, may favour Correspondence to: C. Maffeis Abbreviations: FFM = fat-free mass; RMR = resting metabolic rate; RQ = respiratory quotient; TEM = thermic effect of meal body weight gain [9, 11]. In particular, the possibility that impaired postprandial thermogenesis is an aetio- logical factor associated with some human obesity has received considerable attention during this last decade [1, 3, 4, 21]. However, the contrasting results reported by differ- ent investigators on the thermogenesis induced by food ingestion in obese and lean adults seems to suggest the existence of two subgroups of obese individuals, one with and one without apparent thermogenic defect [10, 201 . On the other hand, studies in both animals [24, 25] and man [2] suggest the importance of heredity on RMR and on thermogenesis in response to various stimuli. The present study was undertaken to examine the RMR and the meal induced rise in energy expenditure in obese prepubertal children with or without familial his- tory of obesity and in non obese controls to detect whether the familial history of obesity could be linked or not to a "thermogenic defect" in the obese children. Materials and methods The investigations were carried out in 26 children divided into three groups: (1) one group consisted of eight obese children with both obese parents (OBz); (2) one group of eight obese children with both lean parents (OB0); and (3) one group of ten normal body weight children. A child was defined as obese when his/her body weight was more than 20% above the weight predicted for height [23]. No child was taking any form of medication. Normal glucose tolerance of obese children was assessed by an oral glucose toler- ance test (OGTT), following the criteria of the American Diabetes Data Group [15]. Exclusively prepubertal children were included in the study group as defined by Tanner [22]. Informed consent was obtained from the parents of all subjects and the protocol was approved by the Ethical Committee of the University of Verona and was in ac- cordance with the Helsinki Declaration of 1975 as revised in 1983. To explore the magnitude of energy intake of each child, the 24 h recall method was used during 2 weekdays and 1 weekend day [6]. This method consists of a careful interview with the mother on the total food ingested by his/her child during the previous 3 days, collected by a dietician. As an aid to quantification of the food consumed, pictures of different food items were presented to the mother as well as various cups, glasses, spoons and food shapes of different sizes.